As with the Revolutionary Guards' increased activity in exporting the Iranian revolution, since Ahmadinejad was elected there has been a similar rapid expansion of Iran's nuclear programme. When Ahmadinejad came to power, Iran's controversial uranium enrichment programme at Natanz had been halted as part of Tehran's attempts to negotiate a deal with the West over its nuclear aspirations. Almost immediately, Ahmadinejad ordered all the seals to be broken and for work to resume on uranium enrichment. For good measure, he sacked the team of negotiators who had been working with European diplomats to resolve the impasse, and ordered their replacements to adopt a more aggressive approach in their dealings with the West.

Ahmadinejad's more confrontational attitude may have succeeded in increasing Iran's alienation from the West, but it has paid dividends in terms of the tangible progress Iran has made in developing its nuclear capability. Unless Tehran has a radical change of heart, most Western intelligence experts believe Iran will have enough enriched uranium to build an atom bomb by the end of this year.

The prospect of a nuclear Iran, given its well-documented support for Islamist-inspired terrorism, is terrifying enough. But add to this Ahmadinejad's apocalyptic vision of the world, which is all part of his belief in preparing the way for the return of the 12th Imam, and it is obvious why resolving the Iran crisis is the most pressing security issue facing the Obama administration that took office in Washington last month.

The new American president is keen to establish a dialogue with Tehran, and Ahmadinejad himself made some encouraging noises towards Mr Obama following his convincing election victory last November, offering his personal congratulations - the first time Iran has issued an official goodwill message to an American leader since the 1979 revolution. But the impact of Ahmadinejad's gesture was immediately undermined when an editorial in the government-owned Kayhan newspaper declared that the "Great Satan's" face had changed colour, but no more. "Obama's view on talks with Iran is not strategic, it is a hostile tactic," the newspaper warned in an editorial marking the anniversary of the storming of the American embassy in Tehran in 1979. "He does not regard talks as a means to reach a solution, but as a way to increase pressure on Iran." Mr Obama may well want to improve relations with Iran. But even his considerable powers of persuasion are unlikely to break through the mindset of a regime that remains steadfastly committed to upholding the banner of radical Islam and implementing the legacy of Khomeini's revolution.